Monday, July 26, 2010

Morning hyperglycemia in Diabetics

There are 2 conditions which can cause this :

1. Somogyi Effect
2. Dawn Phenomenon

1. Somogyi Effect

  • Also known as "rebound hyperglycemia"
  • Usually due to:
    • missed night meals despite taking insulin regularly
    • a person who takes long-acting insulin without supper
    • night/ long-acting insulin dose too high
  • Relative Insulin Excess-> Early morning (2-3am) hypoglycemia -> Body's counter-regulatory mechanism activated -> Hormones (cortisol, glucagon, epinephrine) released to counter insulin effect -> Morning Hyperglycemia
2. Dawn Phenomenon
  • Can occur in normal person
  • Exaggerated response in diabetics
  • In a normal human physiology, counter-regulatory hormones (cortisol, glucagon, epinephrine) are released during early morning hours to sustain blood glucose level without food. These hormones also antagonize insulin effect, hence there is a relative higher insulin resistance during the night.
  • In patients with Type I diabetics esp, insulin production is low, hence there is an exaggerated Dawn phenomenon --> morning hyperglycemia
  • It typically occurs (more often) in Type I diabetic patients during puberty or pregnancy due to marked production of counter-regulatory hormones (cortisol, glucagon, epinephrine, growth hormone), thus also causing exaggerated Dawn phenomenon.

How to differentiate then ?
Check blood sugar levels (Dextrostix) around 2 - 3 a.m. for several nights.
  • If the blood sugar level is low at 2 a.m. to 3 a.m., suspect Somogyi effect (Rebound phenomenon).
  • If the blood sugar level is normal or high at 2 a.m. to 3 a.m., it's most likely Dawn phenomenon.
    (which is even more likely if the patient is a type I diabetic at early onset of puberty/ pregnancy, although Somogyi effect must be ruled out first)
How to prevent/treat ?

Somogyi effect
  • Have regular meals and never skip them.
  • Have a light snack (preferably protein) before bedtime.
  • Go to bed with a glucose level slightly higher than usual.
  • Bring your diabetic logbook (with your result of early morning 2am-3am blood glucose) while consulting your physician, in case your insulin dose may require adjustments.
Dawn Phenomenon
  • Exercise later in the day. It may have more glucose-lowering effect throughout the night.
  • Limit bedtime carbohydrates and try more of a protein/fat type of snack (nuts, peanut butter, cheese, or meat).
  • Talk with your doctor of a possible medication adjustment (usually insulin) to control the higher fasting readings (common in DM Type I at onset of puberty).
  • Eat breakfast to limit the dawn phenomenon’s effect. By eating, your body will signal the counterregulatory hormones to turn off. -> peliknya...
Why bother ?
Good blood glucose control is essential for diabetic patients. The adjustment of medication (insulin) dose depends on which is the culprit, as one needs to lower the blood glucose prior to bedtime (Dawn phenomenon) or increase the blood glucose level prior to bedtime (Somogyi effect). 

Therefore, if the patient is having persistent morning hyperglycemia despite increased insulin dose, suspect Chronic Somogyi.

Thanks to Dr.Ngiu for asking us weeks ago.

Source : Wikipedia, 2 other internet sources (by Alvis Lee) - July 26th, 2010
Edited by Wong Yee Ming - May 15th, 2011


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